Recently, as one of a number of new memory elements that may be successor candidates to a floating gate NAND flash memory, a resistance-change memory (resistive random access memory [ReRAM]) is being intensely studied and developed. The ReRAM cell array is often configured to have a cross-point structure that has a series circuits of variable-resistance elements and diode elements each arranged between interconnections (at an intersection between a word line and a bit line). Further, a nonvolatile semiconductor memory device with large capacity can be configured by laminating cell arrays with the cross-point structure to form a three-dimensional structure.
In the cell array with the cross-point structure, it is necessary to suppress a current flowing through a non-selected cell when the resistance of a selected cell is read by applying a voltage. Therefore, the structure having a variable-resistance element and a non-ohmic element (diode) connected in series is inserted at the intersection between the word line and bit line. Particularly, it is necessary to use a diode having a sufficient rectification characteristic to suppress a reverse current in the non-selected element when the variable-resistance element performs a unipolar operation.
Generally, a pin diode is used as the diode element of the ReRAM cell array. In this case, the film thickness of the diode becomes large and the aspect ratio of the whole memory cell becomes large. For this reason, it is extremely difficult to miniaturize the cell array. Therefore, recently, the configuration obtained by arranging a variable-resistance element and a metal/insulator/metal (MIM) diode in series between the word line and the bit line is reported (for example, see T. Irisawa et al., IEEE Trans. Electron Devices, 53, 2809 [2006]).
However, if the MIM diode is used as the diode element of the ReRAM cell array, the following problem has occurred. That is, since the MIM diode is configured to have a sandwiched insulating film, it is difficult to acquire a large forward current. Further, a problem that it is difficult to obtain a difference between the forward current and reverse current in the MIM diode and a sufficient rectification characteristic cannot be obtained also occurs.